Java.io.Reader.read() Method


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Description

The java.io.Reader.read(CharBuffer target) method attempts to read characters into the specified character buffer. The buffer is used as a repository of characters as-is: the only changes made are the results of a put operation. No flipping or rewinding of the buffer is performed.

Declaration

Following is the declaration for java.io.Reader.read() method.

public int read(CharBuffer target)

Parameters

target − The buffer to read characters into.

Return Value

This method returns the number of characters added to the buffer, or -1 if this source of characters is at its end.

Exception

  • IOException − If the stream does not support mark(), or if some other I/O error occurs.

  • NullPointerException − If target is null.

  • ReadOnlyBufferException − If target is a read only buffer.

Example

The following example shows the usage of java.io.Reader.read() method.

package com.tutorialspoint;

import java.io.*;
import java.nio.CharBuffer;

public class ReaderDemo {

   public static void main(String[] args) {
      String s = "Hello world";

      // create a new Char Buffer with capacity of 12
      CharBuffer cb = CharBuffer.allocate(12);

      // create a StringReader
      Reader reader = new StringReader(s);

      try {
      
         // read characters into a char buffer
         reader.read(cb);

         // flip the char buffer
         cb.flip();

         // print the char buffer
         System.out.println(cb.toString());

         // Close the stream 
         reader.close();

      } catch (IOException ex) {
         ex.printStackTrace();
      }
   }
}

Let us compile and run the above program, this will produce the following result −

Hello world

java_io_reader.htm

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